--- title: "Philae landed on comet 67P 12 years ago today; it bounced twice and still sent back 64 hours of data" url: https://badiyaa.com/philae-comet-67p-landing-anniversary-rosetta/ published: 2026-11-12T17:15:00+00:00 modified: 2026-11-12T17:15:00+00:00 section: Science publisher: Badiyaa --- # Philae landed on comet 67P 12 years ago today; it bounced twice and still sent back 64 hours of data Philae landed on comet 67P on 12 November 2014, bouncing twice before sending 64 hours of data showing hard ice and 16 organic compounds. Twelve years ago today, on 12 November 2014, a washing-machine-sized robot called Philae touched a comet, bounced about 0.6 miles (1 kilometer) back into space, and came down twice more before it stopped. It was still the first soft landing ever made on a comet nucleus, and its 64 hours of data changed what scientists thought these icy bodies are like. The bounce was not in the plan. According to the [European Space Agency lander’s mission record](https://en.wikipedia.org/wiki/Philae_(spacecraft)), the harpoons meant to pin Philae to comet 67P/Churyumov-Gerasimenko never fired, and a thruster built to press it down did not work either. Had Philae left the surface faster than about 17 inches (44 centimeters) per second, it would have escaped the comet’s feeble gravity for good. It rebounded at about 15 inches (38 centimeters) per second. ## A 10-year trip and a 7-hour landing Philae rode on the Rosetta spacecraft, which launched from French Guiana on 2 March 2004 and spent 3,907 days, about 10.7 years, looping past Earth three times and Mars once to build up speed. Rosetta reached the comet on 6 August 2014 and became the first spacecraft ever to orbit one. On landing day the 220-pound (100-kilogram) lander separated at 08:35 UTC. Its first touch came at 15:34 UTC, and the signal took 28 minutes to reach Earth. After two bounces, it settled at 17:31 UTC, tilted about 30 degrees in the shadow of a cliff. That spot got roughly 90 minutes of sunlight per 12.4-hour comet day, not enough to recharge its batteries. ## What 64 hours on the surface revealed Controllers raced to run about 80% of the planned first science sequence before the main battery died. Philae fell silent on 15 November 2014 at 00:36 UTC. Lander manager Stephan Ulamec of the German Aerospace Center said: “This machine performed magnificently under tough conditions, and we can be fully proud of the incredible scientific success Philae has delivered.” The results surprised the team: - **Hard, not fluffy:** the first touchdown site held strong water ice under a granular layer about 10 inches (25 centimeters) deep, and a probe at the final site could barely hammer into ice as hard as solid rock or pumice. - **Organic chemistry:** instruments detected 16 organic compounds, four never seen on a comet before, including acetamide, acetone, methyl isocyanate and propionaldehyde. - **No magnetic field:** Philae’s readings showed the nucleus itself is not magnetized. Philae woke briefly in June and July 2015, sending a first 85-second message on 13 June, then went quiet for good after 9 July 2015. Rosetta finally photographed it on 2 September 2016 from 1.7 miles (2.7 kilometers) up, lying on its side in a dark crack. “We were beginning to think that Philae would remain lost forever. It is incredible we have captured this at the final hour,” said Patrick Martin, the agency’s Rosetta mission manager. Four weeks later, on 30 September 2016, Rosetta itself was steered into a slow crash on the comet to end the mission. ## Why the comet’s water story is still open The orbiter’s results still feed a live debate. Early readings suggested 67P’s water held about three times Earth’s ratio of heavy hydrogen, which seemed to rule comets out as the source of our oceans. A 2024 reanalysis of the [Rosetta data](https://en.wikipedia.org/wiki/Rosetta_(spacecraft)) found a measurement error and concluded the comet’s water looks much like Earth’s after all. Rosetta also found glycine, the simplest amino acid, and large amounts of free oxygen gas around the comet. One comet is a sample of one, so none of this proves where Earth’s water came from. It does keep comets in the running alongside other ideas. Badiyaa has tracked other long-haul spacecraft this month, including [Voyager 1 reaching one light-day from Earth on 18 November](https://badiyaa.com/voyager-1-light-day-shine-bright-morse/), and comet debris lighting up the sky in the [Northern Taurid meteor shower](https://badiyaa.com/northern-taurids-meteor-shower-peak-fireballs/). The mission’s full data set is archived in NASA’s Planetary Data System, and researchers expect to keep mining it for decades, which is how the 2024 water correction surfaced a full eight years after Rosetta went silent. ## Further reading - [Wikipedia: Philae (spacecraft)](https://en.wikipedia.org/wiki/Philae_(spacecraft)) - [Wikipedia: Rosetta (spacecraft)](https://en.wikipedia.org/wiki/Rosetta_(spacecraft)) *Image: DLR German Aerospace Center, CC BY 3.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*